Integer constants are numbers that are used directly in a sketch, like 123. By default, these numbers are treated as int but you can change this with the U and L modifiers (see below).
Normally, integer constants are treated as base 10 (decimal) integers, but special notation (formatters) may be used to enter numbers in other bases.
|2 (binary)||B1111011||leading 'B'||only works with 8 bit values (0 to 255) characters 0&1 valid|
|8 (octal)||0173||leading "0"||characters 0-7 valid|
|16 (hexadecimal)||0x7B||leading "0x"||characters 0-9, A-F, a-f valid|
Decimal (base 10)
This is the common-sense math with which you are acquainted. Constants without other prefixes are assumed to be in decimal format.
Binary (base 2)
Only the characters 0 and 1 are valid.
The binary formatter only works on bytes (8 bits) between 0 (B0) and 255 (B11111111). If it is convenient to input an int (16 bits) in binary form you can do it a two-step procedure such as:
Octal (base 8)
Only the characters 0 through 7 are valid. Octal values are indicated by the prefix "0" (zero).
It is possible to generate a hard-to-find bug by (unintentionally) including a leading zero before a constant and having the compiler unintentionally interpret your constant as octal.
Hexadecimal (base 16)
Valid characters are 0 through 9 and letters A through F; A has the value 10, B is 11, up to F, which is 15. Hex values are indicated by the prefix "0x". Note that A-F may be upper (A-F) or lower case (a-f).
※ NOTES AND WARNINGS:
U & L formatters:
By default, an integer constant is treated as an int with the attendant limitations in values. To specify an integer constant with another data type, follow it with:
- A 'u' or 'U' to force the constant into an unsigned data format. Example: 33u
- A 'l' or 'L' to force the constant into a long data format. Example: 100000L
- A 'ul' or 'UL' to force the constant into an unsigned long constant. Example: 32767ul